Durban - African women, by far the hardest hit by the Aids pandemic, will be able to protect themselves from HIV infection perhaps as early as 2009 if South African research into microbicides is successful, a top researcher said on Thursday.

Abdool Karim, epidemiologist and researcher at the University of KwaZulu-Natal, told a national Aids conference in Durban that results from trials of the vaginal gels that kill the HIV virus or prevent it from replicating should be expected by early 2007, opening the way for possible use by women two years later.

Research into developing a gel that could be used by women to protect themselves against Aids is drawing much attention, in particular in southern Africa where infection rates among young women are double that of men.

"There is no preventative technology at this advanced stage of clinical testing. There is no vaccine," said Karim, who is conducting trials on 300 patients funded by the United States National Institutes of Health and the Bill and Melinda Gates Foundation.

"It is totally under their control. They can insert it and nobody will know. In my studies, none of the men can tell because the gel is so little - it's tasteless, colourless, no smell. There is no way to tell," said Karim.

The gel is contained in a bulb that is inserted into the vagina with a spindle.

Karim said he was cautious about prospects for success, saying it was "a 50/50 call".

He said pharmaceutical companies were not too interested in microbicides because they were not a profit-making venture and that smaller biotech firms were blazing the path to the potentially life-saving technology.

"If they find an effective microbicide, they will be compelled to provide it free to the developing world," he said. "People don't have money to buy it here."

Karim said trials of a new generation of microbicides will be launched next year on 3 200 women in six countries including the United States, South Africa, Zimbabwe and Malawi.

"South African research is at the forefront of microbicides development. They are right at the edge," he said.

He also argued that South Africa should shoulder a large burden of the research and development of microbicides because of "the catastrophic rise of HIV infection in young women" that can reach as high as 50.8% in the 20 to 24 age group in some rural areas.

South Africa has one of the world's highest Aids caseloads, with 5.3 million people, or one in five adults living with HIV or Aids, according to the UN Aids agency.